Removal of the old unit is straight forward. It's all done from the inside. Four bolts hold it to the roof.
Installation was easy for me. Our strong son-in-law came over with his two young lads. We put a long ladder on the side of the RV. I put a sheet of plywood on the ladder and the ac on top of it. We tied a stout rope to the ac. That made it easy to pull the 90-pound ac up the ladder. He then dropped the new unit in the old hole.
There is very little tolerance to get the bolts aligned between the inside frame and the bolt holes. I tried to do it myself but I found if I needed to move the ac right an 1/4 inch I would overshoot by 1/4 inch. I got my grandson back on the roof to adjust the unit while I got bolts in the holes.
The install manual says the bolts should be tightened to 50 pounds. I know of no way to measure tightness on an uncompressed" sponge", the sealing gasket. So I tightened until I could see the gasket compressed about a 1/4 of an inch.
The electric junction box needed to be moved higher to accommodate the new style frame.
Wiring was no problem. Lazy Daze uses 14-3 copper wire. Dometic uses 14 gauge stranded wire. Stranded to solid wire can come loose, I made sure the stranded wire was long enough to wrap around the copper three times, put on wire nuts and taped them so they will not vibrate loose.
Connect the two 12 volt wires that were removed from the old unit to the wires on the new unit. Connect the "phone" connector that leads the thermostat to one of the two female connectors on the new unit. It may make a difference which one needs to be connected. If so, I guessed right.
Now connect the new thermostat. After you do a system reset, the system should work. The reset only requires thermostat be in the Off position, then holding the Mode and Zone buttons while pressing the On button.
If you had the older style analog thermostat that fit flush with the wall you will now have to make a larger hole to accommodate the new thermostat and two of the old screw holes will not be covered. The new style has a "bump" on one side of the backer plate that prevents flush mounting unless you make a hole to fit the bump into. I found I would have to cut into stringers on each side to do that. No way was I going to attempt that. So, I put some wood shims on the backer plate to balance it with the bump and screwed it in place. Yes, I can look sideways and see the screws, not professional, but it's the best I could come up with.
Caveat - The opening LD makes is dead on just enough to accommodate the new frame. There was no such frame on our old unit. A 1/16 of an inch less and I would have had to enlarge the opening. That said, I moved both the "phone" wire and 12-volt power wires out of the way of the forward bolts to prevent chaffing or worse from the bolts.